It has been desired that a communication system that transmits packets be highly reliable such as having a low packet loss rate. Further, in recent years, even when a communication line used between communication apparatuses is a best-effort line, high reliability may be required.
Patent Literature 1 describes a configuration example of a communication network that achieves high reliability. Specifically, in the communication network, a packet transfer apparatus is provided in each of a packet transmitting side and a packet receiving side. Two or more independent paths are established between the packet transfer apparatuses. The packet transfer apparatus on the transmitting side duplicates a packet and thereby generates two or more packets. Further, the packet transfer apparatus on the transmitting side outputs the two or more copied packets to independent paths. Therefore, identical packets are transmitted in two or more independent paths. As a result, even if a packet loss occurs in one of the paths, the packet is transmitted through the other path. Therefore, it is possible to improve a probability that the packet reaches the packet transfer apparatus on the receiving side.